The quantity of data used in a computer system has increased rapidly in recent years. As a storage system for managing such data, a large-scale storage system managed by a RAID (Redundant Arrays of Inexpensive Disks) method for providing huge storage resources as called mid-range class or enterprise class has attracted public attention recently. To use and manage such huge data efficiently, there has been developed a technique for connecting a storage system such as a disk array system to information processors by a private network (Storage Area Network, hereinafter referred to as SAN) to thereby achieve high-speed and large-volume access to the storage system (e.g., see U.S. Pat. No. 5,815,652).
On the other hand, a storage system called NAS (Network Attached Storage) has been developed so that the storage system is connected to each information processor through a network using a protocol such as TCP/IP (Transmission Control Protocol/Internet Protocol) to achieve access at file level from the information processor.